The utility model discloses a little flood peak floating hydroelectric generation device in step power station tributary, form first water course between first support base member and the second support base member, and install first water wheels in the first water course, form the second water course between first support base member and the third support base member, and install the second water wheels in the second water course, the generator is installed to the upper end of first support base member, the input of speed regulation device links to each other with the pivot of water wheels, the output of speed regulation device is connected with the input of generator. This device is through a design simple structure's the little flood peak hydroelectric generation device of miniaturized step reservoir, can be abundant utilize some unsuitable water resource that build the area in large -scale, medium -sized power station, for the clean energy that local people offered convenience, while this device dismouting is simple, convenient to use has very high practical value.